1. Field of the Invention
This invention relates generally to the casting of metal, and more particularly, to an improved method and apparatus for the casting of metal strip or sheet in a continuous operation.
2. Background Information
The metals industry has been developing processes and apparatus for producing an as-cast product that needs little or no additional processing such as hot rolling to reduce it to strip form. One such process that has arisen as a result of this development is the single belt casting process. In this process, molten metal is caused to flow onto a moving horizontal surface in the form of a continuous belt whereupon it solidifies as it moves along with the belt. The elongated solid strip of metal is removed from the continuous belt for further processing as desired.
One major disadvantage of this process is the low cooling rate of the molten metal on the belt. As the metal solidifies upon the belt, an air gap forms between the belt and the strip. These air gaps are poor thermal conductors and result in non-uniform heat transfer from the metal. This leads to poor product quality such as cracking and porosity in the metal.